Conventional injection molding machines have an injection barrel, which is a cylindrical tube, through which molten plastic is forced into a mold. An auger is rotatably driven within a tunnel formed in the barrel, and is displaced longitudinally within the barrel like a ram to allow new injection material to be fed into the barrel. The rotation of the auger/ram conveys the molten plastic to the end of the barrel at which a nozzle is attached. In operation, the nozzle is engaged within a nozzle receiving concavity in a mold and the auger/ram is displaced longitudinally, forcing pressurized plastic into the mold through the nozzle.
Conventionally, the barrel is displaced horizontally and vertically to align the nozzle with the nozzle receiving concavity. The vertical displacement of the barrel aligns the nozzle at the correct height to insert it into the concavity of the mold. The horizontal displacement of the barrel moves the nozzle into engagement with the nozzle receiving concavity of the mold for injection, and then withdraws the nozzle from the concavity to permit opening of the mold for part removal and changing of the molds. This involves removing the mold into which the injection molding machine has injected plastic, and replacing it with a new, empty mold.
Conventional injection molding machines are slidably mounted on tracks to accommodate the horizontal motion of the barrel. The vertical movement of the injection molding machine is normally accomplished by a scissors jack type of mechanism which is manually actuated. One well known machine is mounted to a table having a pair of links pivotally mounted to each end of the table to form a parallelogram. Each link is also pivotally mounted to a base. The table is then pivoted about the links, forming a parallelogram that is made more upright and, in its highest position, becomes a rectangle. The injection molding machine has rotational and translational displacement with this link apparatus, performing both horizontal and vertical displacement.
A problem with conventional injection molding machines, and their means for displacing the barrel with respect to the mold, is the complexity of the apparatus and the time consumed in varying the position of the barrel with respect to the mold. Mold changing occurs frequently, and should be accomplished quickly and accurately.
Therefore, the need exists for an apparatus for displacing an injection molding machine to position its nozzle in the nozzle receiving concavity of a mold. The apparatus should be simple to operate and should align the nozzle quickly and accurately with the concavity of a mold.
It is desired that the apparatus position the nozzle into the concavity, and then be capable of doing numerous horizontal displacement operations to accomplish injection and withdrawal to allow positioning of another mold. The horizontal motion of withdrawing the nozzle from, and replacing the nozzle into, the concavity of each mold should not require vertical realignment when a mold with a concavity height similar to the previous mold concavity is encountered. When a mold with a concavity having a different vertical position is encountered, vertical realignment of the nozzle will desirably be quick and accurate.